<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="./lib/vue-2.4.0.js"></script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="n1">

        <select v-model="opt">
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">*</option>
            <option value="/">/</option>
        </select>

        <input type="text" v-model="n2">

        <input type="button" value="=" @click="cal">

        <input type="text" v-model="result">
    </div>
    <script>
        var vm = new Vue({
            el: '#app',
            data: {
                n1: '0',
                n2: '0',
                result: '0',
                opt: '+'
            },
            methods: {
                cal() {//计算器方法
                    /**switch (this.opt) {
                        case "+":
                            this.result = parseInt(this.n1) + parseInt(this.n2);
                            break;
                        case "-":
                            this.result = parseInt(this.n1) - parseInt(this.n2);
                            break;
                        case "*":
                            this.result = parseInt(this.n1) * parseInt(this.n2);
                            break;
                        case "/":
                            this.result = parseInt(this.n1) / parseInt(this.n2);
                            break;
                    }**/
                    
                    //注意：这是投机取巧的方式，正式开发中，尽量少用
                    var codeStr = 'parseInt(this.n1) ' + this.opt + ' parseInt(this.n2)';
                    this.result = eval(codeStr)
                }
            }
        })
    </script>
</body>

</html>